Porous titanium tooth roots will be maintained in twelve Rhesus monkeys. Clinical evaluations will continue until 3 year data on posterior mandibular implants are obtained. Three monkeys will be sacrificed and autopsied to ascertain the presence of titanium in tissues. Implants and surrounding tissues will be removed by block resection from the 9 remaining monkeys and complete histological analyses performed. Clinical and histological results will be compared. Implants will be examined before and after implantation by optical microscopy, scanning electron microscopy (SEM), and electron spectroscopy for chemical analysis (ESCA). Ten human patients will receive porous titanium implants which will serve as distal abutments for three unit bridges. These implants will be clinically evaluated for 5 years and judgments made as to the feasibility of employing porous rooted implants in humans.